Description
The MTL 8937-HN is a high-performance HART (Highway Addressable Remote Transducer) Multiplexer module. It is designed to provide a digital communication link between HART-compatible field instruments and computer-based management software, such as Asset Management Systems (AMS), while maintaining the integrity of the 4–20mA analog signals.
Product Parameters (Datasheet)
- Model Number: 8937-HN
- Module Type: HART Multiplexer (Slave)
- Number of Channels: 16
- Communication Protocol: HART Revision 5, 6, and 7
- Host Interface: RS485 (via MTL 8939-HP backplane/master)
- Signal Type: 4–20mA DC with superimposed digital HART signal
- Isolation: 50V DC (between channels and to common)
- Power Consumption: < 1.0W at 24V DC
- Mounting: Plugs into the MTL 8000 series backplane
- Operating Temperature: -40°C to +70°C (-40°F to +158°F)
- Humidity: 5% to 95% RH (non-condensing)
MTL 8937-HN
MTL 8937-HN
MTL 8937-HN
Country of Origin
This instrumentation module is engineered and manufactured in the United Kingdom by MTL Instruments (a part of Eaton’s Crouse-Hinds series).
Application Fields
The 8937-HN is a critical component in process plants that utilize smart instrumentation:
- Asset Management: Enabling remote configuration, calibration, and diagnostic monitoring of field transmitters.
- Oil & Gas Refineries: Real-time health monitoring of pressure and temperature sensors in remote locations.
- Chemical Processing: Accessing valve positioner data without interrupting the control loop.
- Predictive Maintenance: Identifying failing sensors before they cause a process trip by analyzing HART device status.
- Power Plants: Centralizing instrument data for large-scale boiler and turbine control systems.
Product Usage Instructions
- Backplane Installation: The module is designed to plug into an MTL 8000 series backplane (typically an 8939-HP). Align the module and press firmly into the connectors until the side latches click.
- Addressing: Use the onboard rotary switches or software configuration to set the specific RS485 address of the module within the multiplexer network.
- HART Software Integration: Connect the RS485 output from the backplane to your PC via a HART-modem or gateway. Configure your FDT/DTM or AMS software to scan the 8937-HN channels.
- Wiring: Field instruments should be connected to the backplane’s corresponding 4–20mA terminals. The 8937-HN “listens” to the digital signal without adding impedance to the analog loop.
- Status Check: Monitor the front-panel LEDs. A flashing “Comm” LED indicates active HART traffic between the module and the field devices.
Product Technical Description
The MTL 8937-HN acts as a transparent bridge. Technically, it uses a capacitive coupling technique to extract the high-frequency Bell 202 digital signals (HART) from the 16 analog loops. Because the multiplexer has a high input impedance to the HART signals, it does not interfere with the primary 4–20mA control signal used by the PLC or DCS. Each of the 16 channels is scanned sequentially, and the data is buffered for high-speed retrieval over the RS485 link to the host workstation. This allows a single PC to communicate with thousands of field devices by daisy-chaining multiple 8937-HN modules.
Q&A (Common Questions)
Q: Does this module interfere with the safety function of the loop? A: No. The 8937-HN is designed for “passive” listening. Even if the module loses power, the 4–20mA analog signal remains intact and operational for the control system.
Q: Can I use this with non-MTL backplanes? A: The 8937-HN is specifically keyed for the MTL 8000 series backplanes. It is generally not compatible with third-party mounting systems.
Q: How many devices can I connect to a single multiplexer network? A: Using RS485, you can typically address up to 31 modules (up to 496 field instruments) per single RS485 port on your computer.
Q: Does it support the latest HART 7 features? A: Yes, the 8937-HN is protocol-transparent and can pass HART 5, 6, and 7 commands between the software and the field device.
Similar Model Recommendations
- MTL 8939-HP: The associated backplane/power module for the 8937-HN.
- MTL 4850: A HART multiplexer designed for DIN-rail mounting and IS (Intrinsic Safety) applications.
- MTL 8937-HN-P: Variant with specific power-on-demand features.
- MTL 5541: Single-channel isolated repeater with HART transparency.
- MTL 8950: Ethernet-based HART gateway for modern network integration.
For technical datasheets or to check current availability for the MTL 8937-HN and other HART communication modules, please contact our support team.
